The invention relates to a brush seal for sealing off components movable relative to one another with respect to a pressure difference, having bristles to which a supporting surface is assigned against which the bristles come to rest which are deflected to the side of the lower pressure.
The use of brush seals for sealing off components, which can be moved relative to one another and, in particular, are rotationally movable, with respect to a pressure difference are sufficiently known. Such brush seals comprise essentially a bristle housing which is disposed in a component of the arrangement to be sealed off and is used for accommodating the bristles. In this case, the bristles are oriented with their free ends toward a sealing surface of the second component of the arrangement to be sealed off and, with respect to the pressure difference to be sealed off, can be supported on a supporting plate arranged in the bristle housing. The cover plate and the supporting plate of the bristle housing are connected with one another and are disposed within a corresponding recess in the first component on the correct side; compare German Patent Document DE 100 18 273 A1.
All brush seals known so far have the common disadvantage that they can be used only for a pressure difference in one direction. However, in industrial applications, a pressure reversal may occur so that the brush seal also has to be effective in the opposite pressure direction. Similar requirements also occur in the case of bearing chamber seals in aircraft engines when no reliable admission of sealing air takes place to the seal under certain operating conditions, for example, below an idling rotational speed.
It is therefore an object of the invention to provide a remedy here by a construction of the bristle housing which permits the use of one and the same brush seal independently of the direction of the pressure difference.
Based on a brush seal of the initially mentioned type, this object according to the invention is achieved in that a bristle housing with one or more bundles of bristles and with at least two surfaces supporting in opposite directions is provided for the purpose of sealing off the components also in the case of a change of the pressure direction.
According to a first embodiment of the invention, the bristle housing consists of two opposite, particularly symmetrically arranged and mutually identical housing halves with legs projecting into the area of the bristle ends, the free ends of the legs having mutually facing supporting surfaces for the bristles.
According to another embodiment of the invention, two bundles of bristles, which are kept separate, are arranged in a bristle housing with two opposite, particularly symmetrically arranged and mutually identical housing halves whose legs have supporting surfaces for the bundles of bristles, if required, with a separating plate between the bundles of bristles.
According to another embodiment of the invention, the bristle housing comprising the bundles of bristles has a formation with a T-like cross-section which has a central leg whose foot area forms opposite supporting surfaces for the bundles of bristles, which are held between plates and the central leg, which plates engage in the leg halves of a leg situated transversely with respect to the central leg.
Finally, it is also conceivable to divide the bristles held by the bristle housing into two bundles of bristles which are assigned to oppositely acting pressure differences and adjoin one another.
By means of the design of the new brush seal according to the invention, it is ensured that there are always bristles which rest against the respective supporting surface in the correct pressure direction. Particularly when the brush seal according to the invention is used as a bearing chamber seal for aircraft engines, this means that a housing ring on the low-pressure side acts as a supporting ring and a housing ring on the high-pressure side operates as a cover ring.
In the last-mentioned preferred embodiment, a bundle of bristles securely comes to rest on the respective supporting surface only starting at a certain pressure difference, so that the full sealing effect is reached only starting at such a pressure difference. However, even this type of an embodiment has a sealing effect which is independent of the direction of the pressure difference.